The self-aligning mechanism for swivel casters described herein in contrast with the structures shown in U.S. Pat. Nos. 1,896,234; 2,021,886; 2,831,699; 2,388,874; and 3,518,714 which are designed principally to prevent displacement of a caster wheel while in contact with the ground, is intended for use on carts that will be used in conjunction with an overhead automatic cart distribution system. In such a system, carts are lifted so that the wheels are not touching the ground and distributed automatically to various areas of the building. It is frequently required of such systems that the swivel casters do not swing out beyond the sides of the cart when lifted from the ground. However, the casters must still be capable of swiveling continuously in either direction when on the ground. The self-aligning mechanism described herein is designed to align the caster while the cart is lifted off the ground and, yet, when the cart is on the ground, to allow the caster to rotate continuously in either direction and virtually as freely as it would if the self-aligning mechanism was not added to the swivel caster.